Arizona Gold & Silver (TSX-V:AZS) has been conducting a metallurgical testwork program which aims to demonstrate the viability of a heap leach operation in tandem with underground development at the Philadelphia Project in the US.
The latest data demonstrates the benefit of high pressure grinding rolls (HGPR) crushing on near surface stockwork gold zones, alongside the amenability of the material to heap leach extraction of gold and silver.
After 199 days of leaching, leaching of a bulk sample crushed by HGPR – a type of comminution equipment to grind ore between two counter-rotating rollers – achieved 76% recovery on gold and 40% of recovery on silver.
Arizona Gold & Silver is targeting 80% recovery of total contained gold within 150 days at -6.3mm.
Leaching is continuing along a nearly linear leach curve, which Arizona Gold says is demonstrating recoveries 16% higher on gold and 12% higher on silver than a parallel column being run using conventional crushing to -6.3mm.
After four days of leaching, recovery attained 51% and 26% on gold and silver, respectively. After 20 days of leaching, 60% and 32% recovery of gold and silver, respectively, was achieved.
Vice President of Exploration Greg Hahn says it is essential that a metallurgical program runs in conjunction to drilling.
“Drilling to date has established that there are substantial volumes of stockwork material above the high-grade zone,” Hahn says.
“That material carries 0.4 to 1.5 grams per tonne gold and is particularly valuable in today’s gold price environment.”
Hahn adds that the column leach tests using HPGR crushing shows the amenability of the near-surface potable stockwork gold zone to heap leach processing.
“This now establishes a path forward for evaluating this material from a mining, processing, and economic perspective.”
Arizona Gold & Silver is continuing core drilling. A new hole will test 60m to the north of a previously drilled hole which returned 20.43m @ 9.04g/t gold and 34g/t silver.
The Philadelphia Project is a gold and silver vein target located in Mohave County, northwestern Arizona.
Write to Aaliyah Rogan at Mining.com.au
Images: Arizona Gold & Silver
